Initially I built a new router machine with an onboard card and USB-ETH adapter and configured USB to be WAN/PPPoE interface and on-board to look into the LAN.

But then I installed a PCIe NIC and wanted it to be the LAN card. For that I removed the LAN IP from the on-board NIC via console and wanted to add it to the PCIe NIC.

That did not work due to an error message stating:

10.0.0.0/8 overlaps with 10.0.0.0/24 (VPN99).

Tried adding the LAN IP back to the on-board card and got the same error.

And I could not find a way to do anything about that from the console, until I switched to another profile, than restored the first profile from backup and switched back there. Then I had to connect the LAN to on-board and live with that.